Mitigating kinetic hindrance of single-crystal Ni-rich cathodes through morphology modulation,nickel reduction,and lithium vacancy generation achieved by terbium doping

Single crystallization has proven to be effective in enhancing the capacity and stability of Ni-rich LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(SNCM)cathode materials,particularly at high cut-off voltages.Nevertheless,the synthesis of high-quality single-crystal particles remains challenging because of severe particle agglomeration and irregular morphologies.Moreover,the limited kinetics of solid-phase Li^(+)diffusion pose a significant concern because of the extended diffusion path in large single-crystal particles.To address these challenges,we developed a Tb-doped single-crystal LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2)(SNCM-Tb)cathode material using a straightforward mixed molten salt sintering process.The Tb-doped Ni-rich single crystals presented a quasi-spherical morphology,which is markedly different from those reported in previous studies.Tb^(4+)oping significantly enhanced the dynamic transport of Li^(+)ions in the layered oxide phase by reducing the Ni valence state and creating Li vacancies.A SNCM-Tb material with 1 at%Tb doping shows a Li^(+)diffusion coefficient up to more than 9 times higher than pristine SNCM in the non-diluted state.In situ X-ray diffraction analysis demonstrated a significantly facilitated H1-H2-H3 phase transition in the SNCM-Tb materials,thereby enhancing their rate capacity and structural stability.SNCM-Tb exhibited a reversible capacity of 186.9 mA h g^(-1)at 5 C,retaining 94.6%capacity after 100 cycles at 0.5 C under a 4,5 V cut-off.Our study elucidates the Tb^(4+)doping mechanisms and proposes a scalable method for enhancing the performance of single-crystal Ni-rich NCM materials.

Efficient Near-Infrared Quantum Cutting in Tm3＋/yb3＋ Codoped LiYF4 Single Crystals for Solar Photovoltaic

Downconversion （DC） with emission of two near-infrared photons about 1000 nm for each blue photon absorbed was obtained in thulium （Tm3＋） and ytterbium （Yb3＋） codoped yt- trium lithium fluoride （LiYF4） single crystals grown by an improved Bridgman method. The luminescent properties of the crystals were measured through photoluminescence excitation, emission spectra and decay curves. Luminescence between 960 and 1050 nm from yb3＋： 2Fs/2--＋2FT/2 transition, which was originated from the DC from Tm3＋ ions to Yb3＋ ions, was observed under the excitation of blue photon at 465 nm. Moreover, the energy transfer processes were studied based on the Inokuti-Hirayama model, and the results indicated that the energy transfer from Tm3＋ to Yb3＋ was an electric dipole-dipole interaction. The max- imum quantum cutting efficiency approached with 0.49mo1% Tm3＋ and 5.99mo1% Yb3＋. increasing the energy efficiency of crystalline energy part of the solar spectrum. up to 167.5% in LiYF4 single crystal codoped Application of this crystal has prospects for Si solar cells by photon doubling of the high

Paramagnetic Anisotropy of CdGd_2(WO_4)_(4-δ) Single Crystal

CdGd2 （WO4）4 -δ single crystal was grown using the Czochralski＇s method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of （WO4）^2- , therefore, there were some Gd^2＋ ions. Langevin paramagnetism and anisotropy were observed from the δ-T curves at room temperature. The susceptibility X//was 3.5018×10^-3, and X⊥ was 3.4403× 10^-2. The anisotropy was also observed in the electron spin resonance （ESR） experiments. The anisotropic Land6 factors were g//= 2. 1333 and g~ = 2. 8411. The direction of easy magnetization was in the α-b plane. Anisotropic paramagnetic Curie constants C//and C⊥ were not only related to macroscopic a that was observed through the experiment, but were also related to J⊥ and J//, which were the microscopic quantum numbers of the Gd^2＋ and Gd^3｜ ions. Based on the detailed analyses, the proportion of 36.8% of Gd^3＋ ions to 63.2% of Gd^2＋ ions in the Gd ions of the CdGd2（WO4）4-δ crystal was calculated, and δ was 0.638 in the single crystal.

Infrared active phonon modes and ionicity of single crystal MgAl2O4

Near-normal incident infrared reflectivity spectra of （100） MgAl2O4 spinel single crystal have been measured at different temperatures in the frequency region between 50 and 6000 cm^-1. Eight infrared-active phonon modes are identified, which are fitted with the factorized form of the dielectric function. The dielectric property and optical conductivity of the MgAl2O4 crystal are analysed. From TO/LO splitting, the effective Szigeti charges and Born effective charges at different temperatures are calculated for studying the ionicity and the effect of polarization. Based on the relationship between the （LO-TO）1 splitting, which represents the transverse and longitudinal frequencies splitting of the highest energy phonon band in the reflectivity spectrum, and the ionic-covalent parameter, the four main phonon modes are assigned. MgA1204 can be considered as a pure ionic crystal and its optical characters do not change with decreasing temperature, so it may be used as a suitable substrate for high-Tc superconducting thin films.

Optical Spectroscopy of Pr3+ Ion Singly Doped LiLuF4 Single Crystal by Bridgman Method

High quality LiLuF4 single crystals doped with various Pr3+ ions were synthesized by a vertical Bridgman method in completely sealed platinum crucibles. The excitation spectra spans from 420 nm to 500 nm. The prepared single crystals exhibit a blue band at 480 nm(3P0→3H4), a green band at 522 nm (3P1→3H5), and a red band at 605 nm (1D2→3H4)when excited at 446 nm;their corresponding average lifetimes are 38.5μs, 37.3μs, and 36.8μs, respectively, which are much longer than those in oxide single crystals. The effects of excitation wavelength and doping concentration on emission intensities and chromaticity coordinates are investigated. The optimal Pr3+ concentration is confirmed to be 0.5%.The temperature dependent emission shows that the emission intensity constantly decreases with the increase of temperature from 298 K to 443 K due to the enhancement of nonradiative quenching at high temperature. The 3P0→3H4 transition is the most vulnerable to temperature, followed by the 3P1→3H5 transition and 1D2→3H4 transition.

Synthesis and Structure of Large Single Crystal of TPAF-AlPO_4-5 Molecular Sieve

A large single crystal of TPAF-AlPO4-5 molecular sieve was synthesized by hydrothermal crystallization in the presence of ammonium fluoride. Starting material composition was · 1 P2O5 · 1 Al2O3 · 2. 2 TPAOH · 1. 7 NH4F ·318 H2O. The crystal size has a hexagonal prism with 80μm across and 500μm length.The structure of tetrapropylarnmonium fluoride - aluminium phosphate type-5 was investigated with X-ray diffraction. The unit cell composition is 12AlPO4 · TPAF, space group P6cc (a= 13. 740(5), c= 8. 474(4) A ). Average bond distances are: P-O 1. 564A and Al-O 1. 640A ,which may be due to the partial disorder of the arrangement of P, Al in the framework. The angles of O-T-O and T-O-T (T?P, Al) are 102-116° and 148-176°, respectively. Residue electron density was not well enough defined to give a precise position for tetrapropylammonium fluoride (TPAF). The template agent, TPA+ cations, situate in the 12-ring channels and F- anions locate in double 4-rings near the 12-ring channels. Fixing atomic positions for the TPAF reduced the unweighted and weighted R, R, from 0. 063 and 0. 082 to 0. 046 and 0. 042,respectively.

Effect of heat treatment on electronic phase in underdoped La_(2-x)Sr_xCuO_4 single crystal

Superconducting La1.937Sr0.063CuO4 crystals grown by the travelling-solvent floating-zone technique were thermally treated under various temperatures and oxygen pressures for moderately adjusting the oxygen content. The response of intrinsic electronic property of the crystals to the change of hole density in La2-xSrxCuO4 in the vicinity of the magic doping of x= 1/16 （= 0.0625） is studied in detail by magnetic measurements under various fields up to 1 T. It is found that when the superconducting critical temperature （Tc） increases with the oxygen content, there appears also a new subtle electronic state that can be detected from the differential curves of diamagnetic susceptibility dx/dT of the crystal sample. In contrast with the intrinsic state, the new subtle electronic state is very fragile under the magnetic fields. Our results indicate that a moderate change in oxygen doping does not significantly modify the intrinsic electronic state originally existing at the magic doping level.

Upconversion Luminescence from Ho3＋ and Yb3＋ Codoped α-NaYF4 Single Crystals

The Ho3＋/yb3＋ co-doped a-NaYF4 single crystal was grown successfully for the first time by a modified Bridgman method in which KF was used as assisting flux and a large temperature gradient （70-90℃ /cm） of solid-liquid interface was adopted. Upconversion emissions at green -544 nm, red -657 and -751 nm were obtained under 980 nm laser diode excitation. The intensity at -544 nm was much stronger than those of -657 and -751 nm. The mechanisms of the upconversion emissions were investigated by studying the relationship between the upconversion intensity and pump power. The optimized Yb3＋ concentration was about 8.08moi% when Ho3＋ concentration was hold at about 1.0mol%. The results showed that Ho3＋/yb3＋ doped α-NaYF4 single crystal was a possible candidate upconversion material for the green solid-state laser.

Ultraviolet laser-induced voltages in LaSrAlO_4 single crystal

Laser-induced ultrafast photovoltaic effect is observed in LaSrAlO4 single crystal at ambient temperature without any applied bias. An open-circuit photovoltage is obtained when the wafer is irradiated by a 248-nm-KrF laser pulse of 20 ns duration. The response time and full width at half maximum of the photovoltage pulse are 6 ns and 19 ns, respectively, indicating that LaSrAlO4 single crystal has potential application in ultraviolet detector.

Single Crystal Growth and Luminescent Properties of Na_5Eu(WO_4)_4

The single crystal growth of stoichiometric host luminescent crystal Na_5Eu(WO_4)_4 has been investigated. Using Na_2WO_4 as a flux,the optimum conditions to grow a pure single crystal by flux-slow-cooling method have been determined.A high optical quality single crystal of dimention 4.5 mm has been grown,which is the largest one as we know so far.The micro-hardness of Na_5Eu(WO_4)_4 single crystal is 3.46×10~3 MPa.Its refractive index is 1.81 in white light wavelength region and the specific gravity is 5.65 g/cm^3.The fluorescent and excitation spectra have been determined and the reason of the fluorescent quench of ~5D_2 and ~5D_1 to ~7F_j of Eu^(3+)can be explained as multi-phonon non-radiation transition.

Optical Characterization of (TMA)₂ZnCl₄Single Crystals in the Normal Phase

The transmittance (T) and the reflectance (R) were measured for (TMA)2ZnCl4 single crystals and hence the absorption coefficient (α), extinction coefficient (Kex.), refractive index (n), real and im-aginary dielectric constants (ε', ε") of (TMA)2ZnCl4 crystals were calculated as a function of photon energy. The analysis of the spectra behavior of the absorption coefficient in the absorption region revealed indirect transition. The dispersion of the refractive index is discussed in terms of the sin-gle oscillator Wemple-DiDomenico model. The single oscillator energy (E0), the dispersion energy (Ed), the lattice dielectric constant (εL) and the ratio of free charge carrier concentration to the ef-fective mass (N/m*) were estimated. The FTIR spectra were recorded to study the functional groups of the as grown and annealed samples.

Single-crystal Cultivation and Structure Analysis of Unstable 1-Azido-2-chloro-4-nitrobenzene

The 1-azido-2-chloro-4-nitrobenzene was prepared by nucleophilic substitution between 2-chloro-4-nitro-1-(trifluoromethylsulfinyl)benzene and sodium azide, and its structure was characterized by NMR spectrum and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group P21/n, Z = 8 and Mr = 198.57. A cultivation process of the single crystal of unstable aryl azide was provided. The group of trifluoromethyl sulfinyl was found for the first time to be a new excellent leaving group of aromatic nucleophilic substitution reactions.

Light Yield Measurements for PbWO_4 Crystals by Single Photoelectron Method

The measurements of light yield of PbWO4 crystals with normal methods may haverelatively large errors because the crystals have a low light yield.Therefore,a single photoelec-tron method with normal radioactive sources is proposed and the measurements for severalPbWO4 samples produced by Beijing Glass Research Institute are reported.

La对CMSX-4单晶合金与型壳润湿性及界面反应的影响

为了获取高质量的含稀土单晶叶片,采用座滴法研究了La含量对CMSX-4单晶合金与陶瓷型壳润湿性及界面反应的影响。实验结果表明,添加90×10^(-6) La时,合金与型壳的润湿角略有下降,合金中仅发现Al与型壳中的SiO_(2)发生反应,形成产物为Al_(2)O_(3);当合金中w[La]达到143×10^(-6)时,合金与型壳的润湿角显著下降,合金中的La和Al都与型壳中的SiO_(2)发生反应;随后继续增加La含量,界面处析出不同La、Al原子比的铝酸镧化合物,润湿角变化不大。由此可见,实验中,143×10^(-6)为CMSX-4单晶合金中La发生界面反应的临界含量,而且,La与SiO_(2)的反应可以提高合金/型壳体系的润湿性。

High-performance 110 kVp hard x-ray detector based on all-crystalline-surface passivated perovskite single crystals

Halide perovskite single crystals(SCs)have attracted much attention for their application in high-performance x-ray detectors owing to their desirable properties,including low defect density,high mobility–lifetime product(μτ),and long carrier diffusion length.However,suppressing the inherent defects in perovskites and overcoming the ion migration primarily caused by these defects remains a challenge.This study proposes a facile process for dipping Cs0.05FA0.9MA0.05PbI3 SCs synthesized by a solution-based inverse temperature crystallization method into a 2-phenylethylammonium iodide(PEAI)solution to reduce the number of defects,inhibit ion migration,and increase x-ray sensitivity.Compared to conventional spin coating,this simple dipping process forms a two-dimensional PEA2PbI4 layer on all SC surfaces without further treatment,effectively passivating all surfaces of the inherently defective SCs and minimizing ion migration.As a result,the PEAI-treated perovskite SC-based x-ray detector achieves a record x-ray sensitivity of 1.3×10^(5)μC Gyair^(-1) cm^(-2) with a bias voltage of 30 V at realistic clinical dose rates of 1–5 mGy s^(-1)(peak potential of 110 kVp),which is 6 times more sensitive than an untreated SC-based detector and 3 orders of magnitude more sensitive than a commercialα-Se-based detector.Furthermore,the PEAI-treatedperovskite SC-based x-ray detector exhibits a low detection limit(73 nGy s^(-1)),improved x-ray response,and clear x-ray images by a scanning method,highlighting the effectiveness of the PEAI dipping approach for fabricating next-generation x-ray detectors.

涡轮叶片材料CMSX-4超温状态组织演变研究

以涡轮叶片用材料CMSX-4合金为研究对象,采用体式显微镜、扫描电镜、维氏硬度计等研究了CMSX-4合金在超温状态下的组织演变以及硬度变化。结果表明:随温度升高,γ′相长大聚集的同时伴随着γ′相回溶,γ′相立方度下降,γ通道变宽。当超温处理温度到达1250℃时,γ/γ′相界面呈锯齿状;当温度达到1300℃后,γ′相全部回溶;当温度达到1350℃时,合金开始初熔,出现大量孔洞与γ+γ′共晶。当在1300℃以下一定温度保温时,随着保温时间的延长,γ′相百分含量逐渐减少并趋于稳定。当温度达到γ′相全部回溶温度时,因重新析出细小的二次γ′相,合金硬度显著升高,最高硬度达458 HV,比原始状态提高约12%。因此,对于过热等异常服役引起组织损伤与退化,可结合叶片宏观形貌、γ′相形态与百分含量、硬度退化情况进行材料损伤程度的评估。

Spectra and Upconversion of Neodymium Tungstate Crystals

The neodymium tungstate single crystals Nd-2(WO4)(3) were grown using the Czochralski method. The energy level scheme of Nd3+, was obtained through the spectral measurement. The upconversion luminescence of the crystals at 457 and 657 nm, corresponding to the (D5/2-->I11/2)-D-4-I-4 and (2)G(7/2)-->I-4(9/2) transitions, respectively, excited by 808 nm of a laser diode, was observed at room temperature. The fluorescence intensity and the excitation light power have a linear relationship at 457 nm and a quadratic relationship at 657 nm.

Synthesis and Crystal Structure of (SiCl_3)_2Fe(CO)_4

The compound （SiCl3）2Fe（CO）4 was synthesized and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P2 1/n with α = 8.287（2）, b = 9.829（2）, c = 9.042（2） A, β = 96.19（3）°, V= 732.2（3） A^3, C4Cl6FeO4Si2, Mr = 436.77, Z = 2, Dc = 1.981 g/cm^3, F（000） = 424, μ（MoKα） = 2.282 mm^-1, the final R = 0.048 and wR = 0.164 for 1109 observed reflections （I 〉 2σ（I））. The crystal structure of （SiCl3）2Fe（CO）4 reveals that the Si（l）- Fe-Si（l）^a sequence is linear and perpendicular to the Fe（CO）4 cross-shaped plane.

Synthesis,Crystal Structure and Fluorescence Property of N-n-butyl-4-[di(bromoethyl)]amino-1,8-naphthalimide

The halogen as a kind of alkylating reagent is used to introduce new group to realize the fluorescence sensors efficient of metal ion detection. The substituent at C-4 position was double bromine, which defined that the halogen as an alkylating reagent should be further researched and detected for Hg2＋. Therefore, the N-n-butyl-4-[di（bromoethyl）]amino-1,8-naphthalimide has been synthesized to detect some metal ions. The title compound has been prepared via substitute reaction and was characterized by IR, 1H NMR, 13 C NMR, and MS. It crystallizes in triclinic, space group P1 with a = 9.0071（18）, b = 9.804（2）, c = 13.073（3）A, α = 73.17（3）, β = 71.73（3）, γ = 62.95（3）°, Z = 2, V = 961.5（3） A3, Dc = 1.666 g/cm3, F（000） = 484, μ（Mo Kα） = 4.232 mm-1, R = 0.0429 and w R = 0.1004. The presence of intermolecular hydrogen bonds as well as π-π stacking interaction led to the stability of the compound. The fluorescence intensity was obviously lower than that of other ions when Hg2＋ was added with the concentration of 1 × 10^-5 mol·L-1.

Synthesis,Characterization,X-ray Crystal Structure and Safener Activity of Chiral 2-(3-Methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl)-2-oxoethyl Acetate

The new title compound, chiral 2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）- 2-oxoethyl acetate, has been synthesized via reduction, cyclization and acylation reaction. The structure of the product has been confirmed by IR, 1H NMR, 13C NMR, LC-MS （ESI） and single-crystal X-ray diffraction. （R）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate crystallizes in monoclinic, space group P21/c with a = 11.867（2）, b = 8.4087（2）, c = 14.325（6） A^°, β = 117.59（2）°, Z = 4, V = 1266.9（6） A^°3, Dc = 1.307 g/cm^3, F（000） = 528, μ（MoKα） = 0.097 mm-1, R = 0.0453 and wR = 0.1237; （S）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate belongs to the triclinic system, space group P with a = 8.2647（17）, b = 8.7034（17）, c = 9.5479（19） A^°, α = 105.33（3）, β = 100.95（3）, γ = 105.14（3）°, Z = 2, V = 614.1（2） A^°3, Dc = 1.348 g/cm^3, F（000） = 264, μ（MoKα） = 0.10 mm-1, R = 0.0613 and wR = 0.1037. Both of the molecules prefer to form crystal packing through C–H…O hydrogen bonds.